Yeah, there's been rumors that a felt ban is coming. Nothing official sounding, though.

That said, we DO have streams with Didymo and are trying to prevent it's spread to other streams which do not (yet) have it. Make a habit of cleaning your gear properly. Not just the boots, but all gear.

Both branches of the Delaware, as well as the main stem have confirmed Didymo. Also, the Youghiogheny River. Nearby "destination waters" in other states with confirmed Didymo include the Battenkill in NY and the Gunpowder in Maryland. I'm sure there's others.

I transitioned to studded rubber with my last pair, was always a felt guy. Are they acceptable? Yes. Are they better than felt? No.

On soil, mud, sand, or snow, rubber is actually an advantage, but for me these conditions are the exception rather than the rule. On gravel, river rock, or any broken surface, a good rubber does just fine, they are probably equivalent. Where you notice the inferiority to felt is on large rocks, boulder-like or flat. Like all those huge boulders you scramble around on smaller, high gradient streams.